#ifndef __UNIT_H__
#define __UNIT_H__

class Unit
{
public:
    static const Unit& getMile();
    static const Unit& getYard();
    static const Unit& getFeet();
    
    friend class Length;
private:
    Unit(int);

    int factor_m;
};

#define MILE Unit::getMile()
#define YARD Unit::getYard()
#define FEET Unit::getFeet()

#endif


